Damn Interesting

Lie Detectors

Law enforcement officers, secret agents, and counter-espionage personnel have most interesting toolboxes. Their occupations center around discovering “the truth” (or a convincing substitute) in environments where truth is scarce, and consequently they make use of methods which attempt to coerce, deceive, or scare the truth out of those who may possess it.

One of the most common interrogation tools in the history of the trade has been the lie detector. Over the years, these machines have helped put people in prison, destroy careers, and possibly even end lives. The Cold War was the heyday of these paranoia-driven truth-hunting techniques, and since the 1980s their popularity in the U.S. has declined. But they’re certainly not gone… if you ever apply for a job with the federal government, particularly a three-letter agency (FBI, CIA, etc), you’re likely to be subjected to a lie detector test, known in the industry as a “polygraph test.” But can these machines actually do what they claim?

In the recent past, polygraph tests were administered with analog polygraph machines that produced their output on paper chart recorders with colored pens; but these days they usually run as software on laptop computers with plug-in polygraph peripherals. Sensors which monitor physiological variables such as blood pressure, heart rate, respiration and skin conductivity are placed on the individual being tested (the “subject”) before questioning begins. Some units include sensors to monitor arm and leg movements as well. The data from these sensors is fed to the monitor, which records them for the polygraph operator.

Before the test is administered, the polygraph operator conducts a pre-test interview to help establish a connection with the subject, and to gain information to be used in forming “control questions.” Control questions are questions which the polygraph operator believes the subject will lie about, such as “Have you ever lied to get out of trouble?” Such questions are intended to establish a baseline reference against the responses to other questions.

The operator will then explain the polygraph machine, informing the subject that it can detect when he/she is lying, emphasizing the importance of answering truthfully. The test then begins, and includes a series of alternating question types. Some questions are the control questions; others are “irrelevant,” such as, “Are the lights on in this room?”; and the rest are questions regarding the investigation at hand. Any time the device records a physiological response greater than that exhibited with the “control” questions, the subject is assumed to have lied.

The test’s post-interview, conducted after the machine is turned off, is often the most telling portion of the process. At this point the interviewer will ask questions in such a way that the subject may believe that he/she has been “caught” by the machine, which may cause them to admit to wrongdoing.

Scientific studies of polygraph results have shown that the machines themselves provide unreliable findings. Physiological response is simply not a reliable indicator of dishonesty, but rather, it indicates increased emotions. For instance, when an important question is asked in an interview, a subject may experience anxiety at the possibility of a “false positive,” causing an emotional response. The reliability of the tests is also cast into doubt by the numerous countermeasures one can use to skew the results.

Findings imply that the success of a polygraph test is largely dependent on the subject’s belief that the technology can discover their lies. If a person is relaxed and has no anxiety of being caught, they can usually lie without detection, so long as they maintain their lies in the post-interview.

A turning point in polygraph usage came in 2001 when a number of workers at the U.S.’s major nuclear weapons laboratories began refusing the congressionally-mandated polygraph tests. A number of scientists and engineers from Sandia National Laboratories, Los Alamos National Laboratory, and Lawrence Livermore National Laboratory lost their security clearance as a result, and the U.S. Department of Energy was suddenly lacking the resources to deal with a nuclear weapons emergency.

That industry’s most outspoken opponent of polygraph screening was Dr. Alan P. Zelicoff, a senior scientist at Sandia’s Center for National Security and Arms Control. He is also a medical doctor, so his opinion carried even more weight. “Every first-year medical student knows that the four parameters measured during a polygraph—blood pressure, pulse, sweat production and breathing rate—are affected by an unaccountable myriad of emotions,” he explained, “But there is not one chapter, not one, in any medical text that associates these quantities in any way with an individual’s intent to deceive.”

Nowadays, very few courts admit polygraph results as evidence, because their accuracy is far too questionable; and laws put in place in the late 1980s prevent private employers in the U.S. from using polygraph tests in employee screenings. Yet the FBI and other federal agencies still utilize the testing widely, despite the very strong evidence that the results are unreliable, and practically useless. Feel free to draw your own conclusions there.

While enlisted in the Air Force, I volunteered to undergo a polygraph test as a result of a missing piece of classified equipment from our secure facility. I don’t know why they even bothered to test me; they had an accurate timeline of when the equipment disappeared, and I wasn’t even in the country when it happened–I was on leave at the time!

I agreed to take the polygraph so that I could “officially” clear my name; however, I really took it just so that I could see how it was done and to say that I did it!
I didn’t think that I would be nervous during the test, but after getting hooked up and being asked a few questions, I started to think, “Crap, what if my wife handed them a list of stuff to ask me?!”

I ended up being rather nervous throughout the entire test, but I “passed” it with flying colors; so I was told…

cedricindra

Posted 09 December 2005 at 04:58 pm

Thanks for the tips on how to pass a polygraph test. I will certainly keep it in mind if i am ever subjected to it. Rest assured I have no ill intentions, but i certainly would love to beat the little sucker.

Dean Booth

Posted 15 April 2006 at 12:46 am

Funny photo — makes me wonder if the questioning might be about implants!

BathroomNinja

Posted 26 July 2006 at 09:38 pm

I had to take a polygraph to get into the local Police department. Knowing that the polygraph is no more accurate than reading bumps on my head, I was a bit nervous. It’s hard to remember to breath when you know that a false positive can keep you from getting a job. I was completely honest, but the examiner was convinced that I was lying. I still got the job, despite having ‘failed’ the polygraph. It probably didn’t help that I told the examiner that the ‘test’ was a load of crap.

mensadave

Posted 26 July 2006 at 11:59 pm

Aside from “false positive” readings, a polygraph may be useless on individuals who are sociopathic (and, thus, may show little or no emotional response to crimes they may have committed) or psychotic (and therefore unaware of the seriousness or consequences of their actions). A better test (though probably not foolproof) would be some kind of brain scan of mental activity triggered by various questions, as lying involves different areas of the brain than truth-telling. A large part of the accuracy of polygraphs also depends on the skill of the person administering the test. BTW, the person who invented the polygraph was the same person who created Wonder Woman– I believe his name was William Marston.

michael

Posted 27 July 2006 at 12:26 am

mensadave said: “Aside from “false positive” readings, a polygraph may be useless on individuals who are sociopathic (and, thus, may show little or no emotional response to crimes they may have committed) or psychotic (and therefore unaware of the seriousness or consequences of their actions). A better test (though probably not foolproof) would be some kind of brain scan of mental activity triggered by various questions, as lying involves different areas of the brain than truth-telling. A large part of the accuracy of polygraphs also depends on the skill of the person administering the test. BTW, the person who invented the polygraph was the same person who created Wonder Woman– I believe his name was William Marston.”

I remember hearing about a technology that used brain scans. As I recall, the scan looked for patterns that signify recognition. So, when shown a photo, a subject either recognizes the contents of the photo, or it’s the first time they’ve seen it. You just show pictures of the crime scene and watch them for recognition.

I can’t imagine a world without lie detectors. The doubleteam of the lie detector and the paternity test has pretty much ensured the existence of US daytime TV for at least a decade now. And how can that be bad?

Crispy

Posted 27 July 2006 at 02:57 am

mushyp said: “…pretty much ensured the existence of US daytime TV for at least a decade now. And how can that be bad?”

LOL.

diacetylmorphine

Posted 27 July 2006 at 03:27 am

Just take a benzo such as Xanax or Valium (Diazepam) before the test.

Kuz_Sam

Posted 27 July 2006 at 04:38 am

LOL…check out this true fact:

Police in Radnor, Pennsylvania, interrogated a suspect by placing a metal colander on his head and connecting it with wires to a photocopy machine. The message “He’s lying” was placed in the copier, and police pressed the copy button each time they thought the suspect wasn’t telling the truth. Believing the “lie detector” was working, the suspect confessed.

Kuz_Sam said: “LOL…check out this true fact: Police in Radnor, Pennsylvania, interrogated a suspect by placing a metal colander on his head and connecting it with wires to a photocopy machine. The message “He’s lying” was placed in the copier, and police pressed the copy button each time they thought the suspect wasn’t telling the truth. Believing the “lie detector” was working, the suspect confessed.”

…yes indeed, for sure for sure by golly, is that one of the major issues concerning the dope problem in this country today is that…there are definitely too many dopes!

nath

Posted 27 July 2006 at 06:10 am

“The history of the lie detector is an interesting one. In ancient India one
favored method was the “donkey tail” system. Suspects were sent into a
darkened hut to pull the tail of a donkey inside. They were warned the donkey
would bray when the guilty person pulled the tail. They were not told the
tail had been covered with soot. The guilty party, according to theory, would
be the one with no soot on his hands.”

This article is interesting but I’m not sure if it is true. I wish there were some kind of device that I could use to … oh, wait.

Drakvil

Posted 27 July 2006 at 08:59 am

If I recall correctly the results of a polygraph test are not admissable in legal proceedings, but an individual’s refusal to take a polygraph test are.

I wonder how a professional polygraph administrator would deal with an Alexithemic subject?

I’m fairly sure I could convince an interrogator that I’m actually from K-pax and will leave Earth on Oct 22, 6:30pm pacific time.

just_dave

Posted 27 July 2006 at 12:36 pm

On an episode of CSI, one of the cops was able to tell that a woman was lying because she looked to her left when “recalling” what had happened to her daughter. Everybody knows that when someone is lying they look to the left, but look to the right when remembering something that had happened.

Heck, Daredevil don’t need no stinkin’ polygraph; he just listens to their hearts.

frenchsnake

Posted 27 July 2006 at 01:21 pm

I’ve always found lying to be a pretty easy task. When my brother and I went to Take Your Child to Work day last year at US Customs and Border Protection, I volunteered to take a polygraph test in front of the other kids. It looked a lot like the picture with the straps across the chest, so it was kind of embarrassing… I lied on almost every question just to test the machine. The inspector said that there wasn’t enough change in most of the answers to hazard a guess one way or the other, and the one question he was sure about was wrong. Liars: 1, Law Enforcement: 0.

mensadave

Posted 27 July 2006 at 01:42 pm

just_dave said: “On an episode of CSI, one of the cops was able to tell that a woman was lying because she looked to her left when “recalling” what had happened to her daughter. Everybody knows that when someone is lying they look to the left, but look to the right when remembering something that had happened.

Heck, Daredevil don’t need no stinkin’ polygraph; he just listens to their hearts.”

I believe, when using this technique, you first have to establish a baseline (i.e., ask some neutral questions first) just as you do with a polygraph, and then red-flag any differences in response behavior, because not everyone conforms to the norm.

another viewpoint

Posted 27 July 2006 at 03:16 pm

just_dave said: “On an episode of CSI, one of the cops was able to tell that a woman was lying because she looked to her left when “recalling” what had happened to her daughter. Everybody knows that when someone is lying they look to the left, but look to the right when remembering something that had happened.

Heck, Daredevil don’t need no stinkin’ polygraph; he just listens to their hearts.”

I’ve heard all sorts of things about body language and lying, however I’ve found that being concious of these things only makes it easier to fudge them.

For example, some people insist that if you’re lying you can’t maintain eye contact with your interrogator and like in that CSI thing, you glance away… I used to be a very accomplished liar when it suited me, and I never found eye contact to be a problem.

And I’d love to take a polgraph test, just to see if I could pass even if I lied. Yeah yeah, lying is wrong etc. but it would be sticking it the man!

Matt Apple

Posted 28 July 2006 at 07:52 am

BTW, the person who invented the polygraph was the same person who created Wonder Woman

I wonder which came first; the lie detector or Wonder Woman? You may remember that Wonder Woman has a “magic lasso” which once wrapped around you compels you to tell the truth.

unique

Posted 30 July 2006 at 07:16 pm

the whole concept of truth assumes the person knows what it is is. Actually it captures how nervous a person is about lying. And some people can lie with you being nervous at all.

tinktoy

Posted 10 August 2006 at 01:39 am

A late post to be sure. DI artical! My son is presently incarcerated in city jail for a crime he did not commit. Falsly accused! Lawyer insisted on $500. polygraph, despite assurances that it would be a dismal failure due to his high blood pressure and genetic heart murmur. Ha! Now the lawyer thinks his client guilty and proceded to hang him out to dry. $4000.00 wasted and now faceing real trial, and no money left for decent councel. Life sucks when your poor and stupid.

tannman

Posted 12 August 2006 at 04:24 am

Scientology uses a type of lie detector in it’s silly E Meter,

Starling

Posted 10 February 2007 at 09:12 am

mushyp said: “I can’t imagine a world without lie detectors. The doubleteam of the lie detector and the paternity test has pretty much ensured the existence of US daytime TV for at least a decade now. And how can that be bad?”

Whenever Maury comes on, I have to resist the urge to throw a shoe at the screen and scream something about lie detectors not being valid evidence in a court of law. I’ve heard that paternity tests are often wrong, as well…

Jeffrey93

Posted 17 March 2007 at 09:12 am

These machines are pretty dumb. They measure your reaction to the question just as much as they measure your reaction to your own answer.

So…ask a shocking enough question…and the answer will always be a lie, since you will react to the question regardless.

Also, like the article said, if you don’t think you’ll be caught you’re golden. Either convince yourself you won’t get caught…or convince yourself what you’re telling is the truth. For a lot of people that would be forced to take these tests, that talent would come easily. For the poor folk that would find this entire ordeal insane….they’ll be labeled as liars and face the consequences.

RageIsTheNewBlack

Posted 07 April 2007 at 06:12 pm

Jeffrey93 said: “These machines are pretty dumb. They measure your reaction to the question just as much as they measure your reaction to your own answer.

So…ask a shocking enough question…and the answer will always be a lie, since you will react to the question regardless.

Also, like the article said, if you don’t think you’ll be caught you’re golden. Either convince yourself you won’t get caught…or convince yourself what you’re telling is the truth. For a lot of people that would be forced to take these tests, that talent would come easily. For the poor folk that would find this entire ordeal insane….they’ll be labeled as liars and face the consequences.”

I wondered how you connected Pinoccio with Disney, when the story was from a 19th century italian novel and the only cartoon versions I was aware of were Japanese, but it seems Disney did actually do a version of Pinoccio…

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